First, some short comments:
I think it's awesome that Nia got to pilot too. And SITTING IN SIMON'S LAP AT THE SAME TIME. She looked pretty badass during the fight. :D
Viral is now Captain Awesome. Blue doesn't look too bad on him anymore. He's even got his own custom-made gloves. And he says one of Kamina's signature lines: "Put in some spirit!" I love that.
Also, I am convinced that he did get Spiral Power in episode 26. In episode 27 he helped pilot Tengen Toppa Gurren Lagann, a monster of a mecha created almost entirely with Spiral Power, and at one point during the battle he pulled two swords out of nowhere to make an attack of his own. Could he have done that without having Spiral Power? I don't think so. Then at the very end, he tossed Lagann at the Anti-Spiral; would he have been able to move Gurren on his own without Spiral Power? I don't think so.
Whyyyyy was this their only on-screen kiss? ;____; I bet they could have shown more if this weren't targeted at a young audience. He should have kissed her hard when he saved her from the Anti-Spiral. Hell, they barely even touched each other the entire third arc. D:
Spiral eye is super awesome.
I guess the reason why Simon couldn't do anything for her, was that by the time they defeated the Anti-Spiral, Nia was already dead (it's not like they had time for anything when the enemy was throwing a friggin Infinity Big Bang in their faces). Afterwards, she was only holding on through sheer will, and it was a miracle she even lasted that long. To try and 'fix' her at that point would be equivalent to raising the dead, and Simon is against playing God because that's what he's been fighting against all this time. The dead are dead and he's learned to accept that, but that doesn't mean they don't live on in his heart.
Nia also went out with no regrets. As far as she's concerned, Simon kept his promise to her: he came for her, she was able to return to Earth and marry him, living her last days as a normal woman (not a doll, not a messenger, just Nia) and leaving the world the happiest she's ever been.
That's why I think it was important that Nia accepted that fate herself and that Simon honored it. Much of her character centered around the fact that she was created as something that shouldn't have self-consciousness, and getting over that to live as a person with her own free will. And I love that moment of silent understanding between them in the cockpit, when Simon realizes what will happen to Nia, and with only a few words, they have mutual acceptance. Talk about an emotional connection.
I do think Simon was pretty heartbroken that he lost her though, even if he knew that it was coming. Just look at his eyes after she disappears. I mean jeez, he got married and barely a minute later he was already a widower. I would have been much happier myself if Nia survived and they lived together for the rest of their lives (though if that happened, there would be complaints that the ending was too cheesy; people would complain no matter what the ending was like). That would have been a happier ending, but what we got was more of an epic ending. Simon's victories have always come with sacrifice; that makes him a bit tragic, but a noble hero nonetheless.
Actually, the Simon/Nia argument in the last episode reminds me of the Fakir/Ahiru argument in the last episode of Princess Tutu. Yes, they could not be 'together' in the natural sense. But they still had happiness, and it is by their choice.
Fakir chooses not to abuse his power by turning Ahiru back into a human, because Ahiru is a duck, that is her true form, and she's accepted it as who she is. In an interview in the second guidebook, Ikuko Itoh says that Fakir would never turn her human, and that even if he asked her, Ahiru would say no. So to do otherwise would make him the same as Drosselmyer, playing with the fates of others.
Similarly, Simon would not abuse his Spiral power to ressurect Nia, because she chose to be killed at Simon's hands along with the Anti-Spiral and peacefully accepted her death. Out of love and out of respect for the dead, Simon would not ignore her wish. So instead he made her as happy as he could in the time she had left. To do otherwise would make him the same as the Helix King and the Anti-Spiral.
Both these outcomes are bittersweet- it's sad, but also terribly romantic. Besides, there are always worse outcomes: I'd rather see Ahiru being with Fakir as a duck than having a tragic ending, and I'd much rather see Nia having those final few days of happiness than getting killed in battle.
Simon's Character Growth:
First of all, I would agree that after his death, Kamina became the soul of the series. His words and spirit became the main philosophy of the Great Gurren Brigade. He was the one who came up with the ideas that set the story in motion, and Simon was the one who made them into reality. That came up again in episode 26, with Kamina reminding Simon of who he is, and Simon following that up by breaking through the dreamworld.
Kamina was Simon's role model and inspiration- however, I wouldn't say that Simon's GAR came from Kamina alone. He had it from the beginning; it was only hidden beneath layers of self-doubt. Hints of his inner badass show up several times in the first arc (episode 7 being a prime example), but for the most part Kamina was the only one who noticed. And then in the second arc we find out that Kamina was just as inspired by Simon as Simon was by Kamina: that mutual belief in each other was what made them such good partners.
I always thought it was interesting how, in the aftermath of Kamina's death, Simon was trying so hard to be like Kamina. At that point he didn't believe in himself, he believed in Kamina (who believed in him), so that's what he thought he had to become to lead the Gurren Brigade. And he failed at it, which made him feel completely useless. It was thanks to Kamina and Nia's words that Simon was finally able to snap out of his depression and start believing in himself.
That carried on into the third arc, when the public no longer believed in him, and yet Simon did not become emo. The difference was that this time, despite all his failures, despite losing everything, he still believed in himself, that what he was doing was right, and that everything he fought for was worth it. He had no regrets. As he said to Viral, "I'm only doing what I'm supposed to."
By then, there was no one else encouraging him; both Kamina and Nia were gone, so he had to be the one to believe in himself. And at the end of the third arc and throughout the fourth, he was the one bringing hope to everyone else.
As for the last episode, I'm satisfied with how we see him at the end, as Simon the Digger. I don't agree with people who call him a "nameless hobo"
When all is said and done, Simon just returned to his origins. Everything started with Lagann, and the final battle ended with Lagann delivering the finishing blow. Everything started with Simon simply digging; the fact that he was an expert digger was the key to his success just as much as the fact that he's got incredible amounts of Spiral Power; so in the end, he'll return to being a simple digger.
That's one of the things I liked most about his character actually, along with his character growth. Personality-wise, he's laid-back and down-to-earth. Even when he was Commander in Chief, he wasn't the type to want power and glory; he just valued the important things in life.
Kamina exploded from the ground like molten lava and burned out just as bright. Simon was the steady digger, who kept moving forward with quiet determination and made Kamina's dreams possible. When a leader was needed, he stepped up to the task and fulfilled his destiny, drilling through every challenge, breaking through every wall, and doing what no one else could. But he still stayed true to himself.
"Who the hell do you think I am? I'm not my brother Kamina. I am myself! Simon the Digger!"
The drill is his soul. It's what he is. He's lived a fulfilled life, is content with what he's accomplished, and at the end he looks up at the sky with a big smile on his face. Simon is a hero, and one of the best protagonists I've had the pleasure of seeing.
Final thoughts on Darker than BLACK will come after I've rewatched the last three episodes. u_u;